High power single frequency for holography

20 Jul 2018

Holography depend on the power, stability and linewidth of a laser to give clear images with a deep field of view. The same is true for interferometry and Brillouin scattering , which has the added requirement for an output without side-bands to the main laser frequency peak.

UniKLasers Ltd, Edinburgh, UK, designs and manufactures single frequency lasers in a wide range of wavelengths using a technique called Bragg Range Michelson Mode Selection (BRaMMS). The technique replaces an end cavity mirror with a volume Bragg grating and Michelson interferometer to create the mode selectivity of a single mode laser. The result is an ultra-stable laser output that is mode-hop and drift free and has a high spectral purity with linewidths well below 500 kHz (coherence lengths well over 100m). Since the VBG reflectivity is limited to a small wavelength range, it can be selected to promote a range anywhere in the output bandwidth of the gain media. This increases the wavelength options available, which means fundamental wavelengths can be used rather than frequency doubled options, the increased efficiency leads to higher available power and reduced thermal management requirements.

With the wavelength now being a function of cavity length, the stability of the output is reliant on reducing fluctuations in the position of the end mirrors. This is easily compensated for by using PZT control linked to a feedback mechanism that corrects any expansion/contraction of the laser head. This feedback loop has the added benefit in that it allows for a fine tunability of the wavelength output, or alternatively locking the absolute frequency to an external reference.

The lasers are therefore ideal for such applications as

* Holography

* Interferometry

* Brillouin Scattering

* Raman Spectroscopy

* Quantum technology

To find out more about the UniKLasers product range, the BRaMMS technique or to get further information please visit our web site here or contact us directly.